Bisthioalkyl glycols

ABSTRACT

Bisthioalkyl alcohols, glycols and derivatives thereof can be prepared by the free radical catalyzed addition of a thiol to an acetylenic alcohol or ester. The novel bisthioalkyl glycols are useful, among other things, as synergists for antioxidants and as intermediates in the manufacture of antioxidants.

United States Patent l :91

Dear et al. 1 Oct. 21, 1975 BISTHIOALKYL GLYCOLS OTHER PUBLICATIONS [75] Inventors: Robert Ernest Arthur Dear, Mount I Kisco; Eduard Karl Kleiner, New g- PP- 55 York, both of NY.

[73] Assignee: Ciba-Geigy Corporation, Ardsley, P i r Examiner-Lewis Gotts Assistant ExaminerD. R. Phillips [22] Filed: Feb. 4 1974 Attorney, Agent, l)r Firm--Luther A. R. Hall [21] Appl. No.: 439,498

[57] ABSTRACT [52] U.S. Cl 260/609 R; 260/609 R; 260/516;

260/535 P; 260/590; 260/594; 260/54 R; Bisthioalkyl alcohols. glycols and derivatives thereof 260/347.2; 260/482 C; 260/518 R; 260/471 can be prepared by the free radical catalyzed addition C; 260/534 R of a thiol to an acetylenic alcohol or ester. The novel [51] Int. Cl. C07C 149/18 bisthioalkyl glycols are useful. among other things. as [58] Field of Search 260/609 R, 609 F, 609 B synergists for antioxidants and as intermediates in-the manufacture of antioxidants. [56] References Cited UNITED STATES PATENTS 13 Claims, N0 Drawings 3,717,618 2/1973 Oswald 260/609 B BISTHIOALKYL GLYCOLS BACKGROUND OF THE INVENTION The attempts of prior artisans to add thiols to acetylenic monoalcohols and to mono and diesters has been attended by low yields, excessive by-product formation or unreasonably long reaction periods to effect complete reaction. References to this effect include 1. K. Yamagishi, T, Tanaka and T. Hoshino, Bull.

Chem. Soc. Japan, 29, 447 (1956);

2. A. T. Blomquist and J. Wolinsky, J. Org. Chem. 23,

3. T. Tanaka, Sci. Repts. Sanitama Univ. Ser A., 3,

DESCRIPTION OF THE INVENTION This invention relates to novel bisthioalkyl glycols and to an improved process for the preparation of bisthioalkyl alcohols, glycols and derivatives thereof, notably the esters.

In one aspect, this invention relates to a method for making a bisthioalkyl alcohol, glycol or ester having two sulfide groups per molecule which comprises reacting, at a temperature of 40 to 100C, in the presence of an azo-type free radical catalyst, from 2.0 to 2.5 moles of a thiol of formula where R is straight or branched chain alkyl of 1 to 24 carbon atoms, phenyl, naphthyl or said alkyl, phenyl or naphthyl substituted by hydroxyl, carboxyl, alkoxycarbonyl of 2 to 24 carbon atoms, phenylalkoxycarbonyl of 8 to 24 carbon atoms, naphthoxycarbonyl, phenyl, phenyl substituted by 1 to 3 of chloro, bromo, hydroxy, alkyl of 1 to 24 carbon atoms, phenoxy, phenylthio, phenyl, phenylalkylene of 7 to 24 carbon atoms, alkylphenylene of 7 to 24 carbon atoms, carboxyl, alkoxycarbonyl of 2 to 24 carbon atoms, phenoxycarbonyl, and phenylalkoxycarbonyl of 8 to 24 carbon atoms,

amino, amino substituted by one or two of alkyl of 1 to 24 carbon atoms, phenyl, alkylphenylene of 7 to 24 carbon atoms or phenylalkylene of 7 to 24 carbon atoms,

furfuryl, carbamyl or carbamyl substituted by one or two of alkyl of 1 to 24 carbon atoms, hydroxyalkyl of 1 to 24 carbon atoms, phenylalkylene of 7 to 24 carbon atoms, phenyl, and alkylphenylene of 7 to 24 carbon atoms;

with 1 mol. of an acetylenic compound of formula where R is hydrogen, straight or branched chain alkyl of 1 to 12 carbon atoms or a group of formula R and R each independently are straight or branched chain alkylene of 1 to 12 carbon atoms; alkylene of 1 to 12 carbon atoms substituted by l or 2 of phenyl, and cyclohexyl, or a group of formula where m is an integer from 1 to 12,

k is an integerfrom 2 to 6, and

r is an integer from 1 to 40;

R is hydrogen; alkyl of 1 to 24 carbon atoms, phenyl, naphthyl, phenyl or naphthyl substituted by l-' to 3 of chloro, bromo, alkyl of 1 to 6 carbon atoms alkoxy of 1 to 6 carbon atoms or alkanoyl or alkanoylamino of 2 to 6 carbon atoms; alkanoyl of 1 to 24 carbon atoms; alkanoyl of 1 to 24 carbon atoms substituted by phenyl or naphthyl, said phenyl or naphthyl being unsubstituted or substi tuted by l to 3 ofchloro, bromo, alkyl of 1 to 6 carbon atoms or alkoxy of l to 6 carbon atoms; benzoyl or benzoyl substituted by 1 to 3 of chloro, bromo, alkyl of l to 6 carbon atoms; alkoxy of 1 to 6 carbon atoms and alkanoyl of 1 to 6 carbon atoms; or 1.2-epoxy alkyl of 3 to 6 carbon atoms.

In another aspect, the invention relates to bisthioalkyl glycols of formula where R,, R and R are as previously defined.

Useful bisthioalkyl glycols include those where R, is alkyl of 6 to 18 carbon atoms or said alkyl substituted by phenyl, chlorophenyl, alkylphenylene of7 to 18 carbon atoms, alkoxycarbonyl of 2 to 20 carbon atoms, amino, amino substituted by 1 or 2 of alkyl of 1 to 4 carbon atoms or hydroxyalkyl of 1 to 4 carbon atoms, or where the alkyl substituent is furfuryl, carboxyl or hydroxyl.

Preferred bisthioalkyl glycols are those where R, is alkyl of 6 to 18 carbon atoms or alkoxycarbonyalkylene of6 to 21 carbon atoms and R and R are each independently a straight or branched chain alkylene of 1 to 4 carbon atoms or a group of formula where m is an integer from 1 to 4;

k is an integer from 2 to 4, and

r is an integer from 1 to 20 Compounds that are particularly preferred are those in which R and R are both alkylene of 1 or 2 carbon atoms or a group of formula where m is an integer from 1 to 2;

k is an integer 2, and

r is an integer from 1 to 20 Compounds that are especially preferred are those in which R is alkyl of 6 to 18 carbon atoms and especially where R, is alkyl of 6 ton 18 carbon atoms and R and R are both alkylene of 1 or 2 carbon atoms.

As indicated, the compounds described herein can be obtained by the free radical catalyzed addition reaction of a thiol of formula R SH with an acetylenic. compound of formula R5 C E R2"OR4 where R,, R R R and R, areas previously described. In the case when the acetylenic compound of formula is used, R and R each preferably is a straight or branched chain alkylene of l to 6 carbon atoms; said alkylene substituted by l or 2 of phenyl, or cyclohexyl, or a group of formula where m is an integer from 1 to 4; k is an integer from 2 to 4, and r is an integer from 1 to 20 and R is as previously defined, in the presence of from 0.5 to 20 percent ofa mol of an azo-type free radical catalyst. in a preferred embodiment of this configuration, the acetylenic compounds have the formula where R R,, R, and R are selected from hydrogen, alkyl of 4 themselves can be converted to the hydroxyalkyl esters, followed by free radical addition of the thiol Similarly, the esters can be made by alternate routes. The bisthioalkyl glycol can be esterified by well-known synthetic organic methods, such as treatment of the bisthioalkyl glycol with a carboxylic acid anhydride, an acyl halide or a carboxylic acid. Altemately, the thiols R,SH can be added to the acetylenic ester.

The ethers can be prepared by the Williamson synthesis and the well-known variations thereof.

The epoxides can be prepared by reaction with an appropriate halohydrin, such as epichlorohydrin.

For additional insight into the chemistry of acetylenic compounds, one might consult Chemistry of Acetylenes by H. G. Viehe, Marcel Dekker, Inc., N.Y. I969 and Acetylenes and Allenes by T. F. Rutledge, Reinhold Book Corp., 1969.

The following acetylenic diols and esters are commercially available:

2-butyn-l ,4-diol 3,4-dimethyll -pentyn-3,4-diol 2,5-dimethyl-3-hexyn-2,5-diol 3-hexyn-2,5diol 3,6-diethyl-4-octyn-3,6-diol 2,6-dimethyl-4-octyn-3,6-diol 2,3,6,7-tetramethyl-4-octyn-3,6-diol 4,7-dimethyl-5-decyn-4,7-diol 2,4,7,9-tetramethyl-5-decyn-4,6-diol 2,4,7,9-tetramethyl-5-decyn-4,7-diol ethylene oxide adducts of Z-butyn-l ,4-diol l,l ,4,4-tetraphenyl-2-butynl ,4-diol 2-butynediol diacetate Monoalcohols, and monoesters can be prepared in a manner analogous to the glycols. Thus, a thiol of formula Reference:

Acetylene Homologs and Derivatives" by Prof. Pierre Piganiol. Pages 295-300. Mapleton House Publishers. Brooklyn. N.Y. Copyright 1950.

The acetylenic compounds where the substituents are such unsaturated groups as vinyl, allyl and styryl are not preferred because these groups compete for the thiol and yield less desirable by-products.

Compounds where R, and R are C,,,H ,,,(OC, H can be made in several ways. For example, the bisthioalkyl glycols where R, is hydrogen can be reacted with a suitable alkylene oxide, such as ethylene oxide, propylene oxide, etc., in the presence of an acidic or basic catalyst. Alternatively, the original acetylenic diols can be reacted with an acetylenic compound of formula where R is straight or branched chain alkyl of l to 12 carbon atoms, or hydrogen and where R, is branched or straight chain alkylene of l to 12 carbon atoms, to obtain the monoalcohol or ester of formula Additional thiols include benzenethiol, p-tert.-butylbenzenethiol, o-amino-benzenethiol, 2-aminc-4-chlorobenzenethiol,

p-chlorobenzenethiol, o-mercaptobenzoic acid,

2-mercaptoacetanilide, o-,mand p-toluenethiol,

toluene-3,4-dithiol, 2,4-xylenethiol, 4,5-dimethyl-oxylene-a,a-dithiol, l-naphthalenethiol, Z-naphthalenethiol.

The process of this invention involves the combination of a. from 0.5 to percent of a mole of an azo-type free radical catalyst;

b. moderate reaction temperatures, on the order of 40 to 100C; and

c. A mole ratio of thiol to acetylenic alcohol or ester of from 2.0 to 2.5 moles of thiol per mole of acetylenic compound.

It is particularly preferred to use from about I to about 10 percent of a mole of azo-type free radical catalyst.

The reaction temperature and choice of azo-type free radical catalyst are considered to be mutually dependent. The temperature range of 40 to 100C is one wherein the formation of undesirable by-products is minimized and wherein the reaction products are stable. In order to achieve a reasonable reaction rate at these temperatures, it is desirable to use an azo-type catalyst that is reactive to a reasonable extent in this temperature range. It is therefore preferred to use an azo-type free radical catalyst having a 1-hour half-life temperature of to about 100C. These compounds are listed below.

Compound 1 Hr. Half-Life Temperature C 2-t-butylazo-2 hydroperoxy-4- C methylpentane 2-t-butylazo-2-cyano-4-methoxy- 74C 4-methylpentane di-t-butyl-4,4'-azobis-(4cyano- C (azo) peroxyvalerate) azobisisobutryonitrile 81C 2-t-butyIazo-2-cyano-4-methylpentane 88C 4-t-butylazo-4-cyanovaleric acid 93C(trichlorobenzene) l,3dimethyl-3-(t-butylperoxy)- 94C (azo) butyl-4-t-butylazo-4-cyanovalerate t-butyl peroxy-4-t-butylazo-4- 94C (azo) cyanovalerate ethylene bis(4-t-butylazo-4- 94C cyano-valerate) Z-(t-butylazo) isobutyronitrile 97C 4-( 4-t-butylazo-4-cyanovaleryloxy l00C Z-hydroxybenzophenane 2-t-butylazo-2-cyanobutane 104C dium, is usually preferred. However, if solvents are 5 bons as the hexane, heptane, octane, higher homologs and cyclohexane, such aromatic hydrocarbons as benzene, toluene, xylenes; blends of aliphatic, cycloaliphatic and aromatic hydrocarbons; alcohols such as ethanol, n-propanol, isopropanol, t-butanol and methyl 0 cellosolve; ethers, both aliphatic and alicyclic including di-n-propyl ether, di-butyl ether and tetrahydrofuran. In addition, chlorinated solvents such as di-chloroethyl ether, ethylene dichloride, perchloroethylene and carbon tetrachloride can be employed.

Using the reaction parameters indicated above, and continuing until reaction is complete, usually after6 to 10 hours using azobisisobutronitrile at 75C, there can be effected an to percent conversion of the thiol to the desired bisthioalkyl alcohol, glycol or ester. Further, the overall yield can be increased because unreacted thiol can be recovered and recycled. Since the addition products are generally poorly soluble in aliphatic and aromatic hydrocarbon solvents, and the thiols are soluble in these solvents, the unreacted thiol can be recovered by washing the product with a solvent such as benzene, heptane and the like.

The formation of the bisthioalkyl alcohols glycols and esters proceeds via the formation of intermediates which may be present as by-products in the ultimate 0 material. These intermediates have the formula among other things as intermediates to manufacture esters of hindered phenolic carboxylic acids of general formula and -continued where R,, R and R are as previously defined R and R, each is selected from lower alkyl of 1 to 6 carbon atoms such as methyl, ethyl, isopropyl and t-butyl p is an integer from to 6, preferably 0 to 2.

The esterification is effected under conventional and well-known reaction conditions. The esters are highly effective antioxidants for organic materials subject to oxidative deterioration such as lubricating oils, waxes, greases, soaps, cutting fluids, synthetic ester lubricants, natural and synthetic rubbers and synthetic polymers such as those derived from vinyl halide, styrene, alkylenedienes such as butadiene and isoprene, a-olefins such as polyethylene and polypropylene.

The esters described above are typically employed in an amount of from 0.01 to about percent by weight of stabilized composition, usually from 0.05 to about 2 percent and can be incorporated before or after polymerization or during fabrication or processing steps e.g., hot milling, extrusion etc.

The antioxidant compounds described above can be used in conjunction with other materials normally used with the organic materials such as dyes, pigments, chelating agents, heat and light stabilizers, antiozonants, plasticizers, emulsifiers, antifoaming agents, corrosion and rust inhibitors, pour point depressants, detergents and emulsifiers and the like.

The efficacy of antioxidant compositions is evaluated as follows: unstabilized polypropylene power (Hercules Profax 6501 is thoroughly blended with 0.2 percent by weight of stabilizer. The blended material is milled on a two-roll mill at 182C for 10 minutes, at which point the stabilized polypropylene is sheeted from the mill and allowed to cool.

The milled polypropylene sheets are then cut into pieces and pressed for 7 minutes on a hydraulic press at 218C, 2,000 psi (140 kg/cm The resulting plaques of 25 mil thickness are tested for resistance to accelerated aging in a forced draft oven at 150C. When the plaques show the first signs of decomposition, such as cracking or brown edges, they are considered to have failed.

Unstabilized polypropylene fails in about 3 hours. Polypropylene stabilized with a composition as described above, namely 2,3bis(dodecylthio)-l-propyl- 3'-[3",5"-di-t-butyl-4"-hydroxyphenyl] propionate of formula HO CH CH COCHAIIHCH SC H SCIZHZS C(CH3):

fails at the end of 645 hours.

The esters, the case when R, is acyl, can be used to prepare the above compositions by well-known transesterification techniques.

The ethers, obtained when R, is alkyl, aryl and the like, are useful as potentiators or synergists for conventional antioxidants, such as the hindered phenols.

The epoxides having one of two 1,2-epoxy groups per molecule are useful to prepare crosslinked epoxy resins by well-known methods.

The invention is further illustrated by the following exampels:

EXAMPLE 1 2,3 -Bis( n-Dodecylthio )propan- 1 -ol C H sCH- n-Dodecanethiol (300g; 1.48 mole) and propargyl alcohol (753g; 1.35 mole) were stirred together with the application of external heat in a 1 litre Morton flask, under nitrogen. After the temperature had stabilized at azobisisobutyronitrile catalyst (7.2g; 0.044 mole) was added in five equal portions of 1.44 g each over a 2 hour period. The reaction was continued for a further 6 hours (8 hours total) and the crude reaction mixture was purified by passage through a falling film molecular distillation apparatus at and 0.02 mmHg. This procedure allowed the recovery of 35g unreacted dodecanethiol and 321g 2,3-bis(n-dodecylthio)prpan-l-ol. This represents a conversion of 88.3% and a yield of 94.9% based on thiol. A sample of the product was further purified by distillation at 200 and 0.0] mmHg. The infrared spectrum shows a broad O-H stretching frequency at 3437 cm and CH stretching frequencies at 2954 cm, 2929 cm and 2853 cm". A further CH band was present at 1465 cm. The proton nmr spectrum further confirmed the identity of the product, showing peaks at O.8l .8 ppm (46H), 2xC H 2.453.0 ppm (8H), 3xCH S, OH, CHS; 3.74 ppm (2H) OCH Elemental Analysis: calcd C H OS :%C70.37;%H12.25;%S13.9l.

EXAMPLE 2 2,3-Bis( n-Octylthio )propan- 1 -ol for C H SCH In a sealed ampoule, in 10 ml. heptane, n-octanethiol (10g; 0.068 mole) and propargyl alcohol (1.74g; 0.031 mole) were heated with azobisisobutyronitrile (0.22g; 0.0014 mole). The reaction was maintained at 70 for 20 hours. The crude product was distilled to give 9.2g 2,3-bis(n-octylthio)propan-1-ol, bp. 180 at 0.01

*1 1 mmHg. Yield=85.2%. The infrared and nmr spectra were very similar to those of Example 1.

Elemental Analysis: calcd C H OS :%C65.45;%Hl1.56;%S18.39. found: %C65.84;%H11.70;%S18.70.

EXAMPLE 3 2 ,3-Bis( n-Octadecylthio )propan- 1 -ol for C H SCHCH OH EXAMPLE 4 to 16 The following examples show the wide variety of solvents which may be employed in the reaction.

In each Example, n-octanethiol (5g; 0.034 mole) was heated in an ampoule with propargyl alcohol (0.83g; 0.015 mole) azobisisobutyronitrile (0.1 12g; 0.0007 mole) and ml solvent. After 18 hours at 75 the contents of each ampoule were examined by gas-liquid chromatography (GLC). The area unreacted thiol, 2,3-bis(n-octylthio)-propan-1-ol and unknowns were calculated.

In a 500 ml Morton flask, n-dodecanethiol (300g; 1.48 mole) and 2-butyn-l,4-diol (608g; 0.71 mole) were stirred together, under nitrogen, at 75, and azobisisobutyronitrile (24g; 0.146 mole) was added in 6 equal portions of 4g each, over a 4 hour period. The reaction was continued for 8 hours. The crude product was passed through a molecular distillation apparatus at 100 and 0.05 mmHg. This procedure gave 19.5g recovered thiol (6.5%) and 322g 2,3-bis(n-dodecylthio) butane-1,4-diol (92.4% A sample of diol was purified further by recrystallization from ethanol and melted at 47-48.

Infrared spectrum showed O-H stretching frequency at 3355 cm, C-H stretching frequencies at 2941, 2930 and 2853 cm. A further C-H band was present at 1462 cm.

Nmr showed signals at: 0.9 ppm(6H) 2xCH 2.32 ppm(OH) 2x(CH 2.65 ppm(4H) 2xSCH 3.02(2H) 2xSCH; 3.20 ppm(2H) 2xOH; 3.88 ppm(4H) 2.xOCH2.

Elemental Analysis: Calcd for C H O S C6851; H1 1.91; $13.06. Found: C6872; H11.89; $13.18.

EXAMPLE 18 2,3-Bis(n-Octylthio)butane-1,4-diol C H SCHCH OH C l-1 5C HC H OH In a glass ampoule, n-octanethiol (10g; 0.068 mole) and 2-butyn-1,4-diol (2.71g; 0.032 mole) were sealed with azobisisobutyronitrile (1.12g; 0.0068 mole) and heated, with shaking at 75 for 10 hours. The resultant oil was distilled. The major fraction was 2,3-bis(noctylthio)butane-1,4-diol boiling at 230 and 0.01 mmHg. Yield=9.6g (79.2%). The infrared and nmr mainly monoadduct. C,.H,,SCH=CHCH,OH. In these cases the principal product was the disulfide. (C,.H S),.

It can be seen that those chlorinated hydrocarbons which contain more than one chlorine atom on the same carbon, notably perchloroethylene and carbon tetrachloride are less effective under the reaction conditions employed herein than are the other solvents.

EXAMPLE 1? 2,3-Bis(n-D0decylthio)butane-1,4-diol c n scticn ou c a scn cn on spectra were very similar to those of the previous example.-

Elemental Analysis: Calcd for C H O S :C63.44; 1111.18; $16.93. Found: C6377; 1111.46; $16.94.

EXAMPLE 19 2,3-Bis(n-Octadecylthio)butane-1,4-diol C H SCl-1CH OH C H SCHCH OH Elemental Analysis: Calcd for C H O S :C72.88; 1O

H12.54; 89.73. Found: C7295; H1280; $9.68.

EXAMPLE 20:

2,3-Bis(n-Dodecylthio)butane-1,4-(polyhydroxye- 15 thyl)diol In a 300 ml Morton flask, n-dodecanethiol (142.9g; 0.71 mole) and the hydroxyethyl ether of 2-butyn-1,4-

diol (51.6g; 0.321 mole if n=1) were heated and stirred 25 under nitrogen at 75. Azobisisobutyronitrile (1 1.64g; 0.071 mole) was added in equal portions over a 4 hour period and the reaction was continued at 75 for a total of 16 hours. The crude product at this stage weighed 190.1g and GLC analysis showed it to contain (area 30 16.2% thiol, 7.4% monoaddition product and 76.5% diaddition product. The mixture was purified by passing it twice through a molecular still at 130 and 0.005 mmHg. This gave 138.3g product, containing 9.78%

14 The infrared and nmr spectra confirmed the structural assignment.

Elemental Analysis: Calcd (based on variation in n as shown by GLC) :C66.71; H11.55; $11.39. Found:

5 C66.35;H11.19;S11.03. Molecular Weight (Hydroxyl titration) calcd: 565 (n=1). found: 546.

EXAMPLE 21 2,3-Bis(n-Dodecylthio)butane-1,4-(polyhydroxyethyl )diol) C H SCHCHAOCH CH ),,OH

n average (56.5g; 0.1 mole) is added to a flask fitted with a mechanical stirrer, a gas inlet tube and a reflux condenser maintained at 78C. Sodium hydroxide (1g; of 50% solution) is added as a catalyst and ethylene oxide gas passed into the flask at 90-l00 for a period of six hours. A total of 82g of ethylene oxide is absorbed, indicat ve of the formation ofa polyether with an average structure of C H SCHCHAOCH CH OH C H SCHCH (OCH CH- OH The product is a clear viscous oil at room temperature.

EXAMPLES 22-42 When two moles of the indicated thiol are reacted with 1 mole of the indicated acetylenic compound under the reaction conditions of Example 1, there is monoaddition product and 90.22% diaddition product. 35 obtained the indicated product:

Acetylene Product Example Thiol 22 C H SH 23 C,H SH

24 C H -,SH

2S C H ,SH

28 C H OOCCH SH 29 HOOCCH:CH SH 30 CHJOOCCH2CH2SH 31 HOCH CH SH 32 E o 1 CHESH I 33 C H OOCCH CH SH 34 (C H J NCH CH SH 35 CzHsOOCCHzSH CH SCHCH2OH O U CH SCH HC ECCH 0H HC E CCHZOH CHHMOOCCHZCHZSCHCHZOH c,ta ooccinci-lzsca HC HZ (czuaizucn cu scucmon HOCH CE CCH OH C H OOCCH SCHCH OH -continued Example Thiol Acetylene Product 36 HOOCCH SH HOCH C E (CH OH HOOCCH SCHCH OH HOOCCH SCHCH OH 37 HOOCCHlCHQSH HC i CCH OH HOOCCH(CH )SCHCH OH 38 C H OOCCH CH SH HOCH C I CCH OH 39 C H SH HC E CCH OCOCH 40 C H SH CH COOCH C E CCH O COCH 41 HOCH CH SH HC 5 C(CH OH 42 C H SH HOCH C CCH OH EXAMPLE 43 This example illustrates the preparation of esters of hindered alkyl phenols, which esters are useful as antioxdiants. v

A reaction flask was charged with 10.82 grams (0.037 moles) of methyl 3-(3 ',5'-di-t-butyl-4'-hydroxyphenyl)-propionate, 16.13 grams (0.035 moles) of 2,3- bis(n-dodecylthio)-1-propanol, the compound of Example 1, 0.059 grams (0.007 moles) oflithium hydride and 2.0 ml of dry dimethyl sulfoxide. The reaction mixture was heated at l40l50C for hours at ambient pressure and then for an additional 3% hours at about lmm. At the end of this period, the catalyst was neutralized with glacial acetic acid (0.43 ml, 0.007 moles) and the product isolated by means of chromatography from silica gel. After drying to constant weight the product, which was a light yellow oil gave the following analysis:

Calculated for C H O S C, 73.26; H, 11.20; S, 8.89. Found C, 73.63; H, 11.47; S, 8.71.

What we claim is:

l. A compound of the formula wherein R and R are each independently straight or branched alkylene of 1 to 12 carbon atoms; alkylene of 1 to 12 carbon atoms substituted by one or two of phenyl, lower alkyl of l to 4 carbon atoms or cyclohexyl; or a group of the formula where m is an integer from 1 to 12,

k is an integer from 2 to 6, and

r is an integer from 1 to 40.

2. A compound according to claim 1 wherein R, is alkyl of 6 to 18 carbon atoms, and

R and R are each independently straight or branched chain alkylene of 1 to 4 carbon atoms or a group of the formula where m is an integer from 1 to 4,

C H OOCCH CH SCHCH OH C H SCHCH OCOCH C H SCH C H SCHCH OCOCH HOCH CH SCH C H SCHCH OH C H SCHCH OH k is an integer from 2 to 4, and

r is an integer from 1 to 20.

3. A compound according to claim 2 wherein R is alkyl of 6 to 18 carbon atoms, and

R and R are both alkylene of l to 2 carbon atoms or a group of the formula where m is an integer from 1 to 2,

k is 2, and

r is an integer from 1 to 20.

4. A compound according to claim 2 wherein R, is a straight or branched chain alkyl of 6 to 18 carbon atoms.

5. A compound according to claim 2 wherein R and R are both alkylene of l or 2 carbon atoms.

6. A compound according to claim 5 wherein R is alkyl of 6 to 18 carbon atoms.

7. A compound according to claim 2 wherein R and R are both a group of the formula m 2Y"( k 2k)T where m is an integer from 1 to 2 k is 2, and

r is an integer from 1 to 20.

8. A compound according to claim 7 wherein R, is alkyl of 6 to 18 carbon atoms.

9. The compound according to claim 1 which is 2,3- bis(n-dodecy1thio)-1,4-butanediol.

10. The compound according to claim 1 which is 2,3- bis(n-octylthio)-1,4-butanediol.

l 1. The compound according to claim 1 which is 2,3- bis(n-octadecylthio)-1,4-butanedio1.

12. The compound according to claim 1 which is where n is an average of 1.

13. The compound according to claim 1 which is 'where n is an average of 10.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,914,319 DATED October 21, 1975 WVENTOMS) Robert Ernest Arthur Dear, Eduard Karl Kleiner it IS certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

0 Column 15, line 49 (in claim 1) after "wherein" insert the following definition of R carbon atoms, phenyl, naphthyl or benzyl, or said alkyl,

is a straight or branched chain alkyl of l to 24 phenyl, naphthyl or benzyl being substituted by l to 3 of chloro, bromo, hydroxyl or alkyl of l to 24 carbon atoms,

and

Signed and Scaled this sixth D y of January 1976 [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner njParenrs and Trademarks 

1. A COMPOUND OF THE FORMULA R1-S-CH(-R2-OH)-CH(-S-R1)-R3-OH WHEREIN R2 AND R3 ARE EACH INDEPENDENTLY STRAIGHT OR BRANCHED ALKYLENE OF 1 TO 12 CARBON ATOMS ALKYLENE OF 1 TO 12 CARBON ATOMS SUBSTITUTED BY ONE OR TWO OF PHENYL LOWER ALKYL OF 1 TO 4 CARBON ATOMS OR CYCLOHEXYL OR A GROUP OF THE FORMULA
 2. A compound according to claim 1 wherein R1 is alkyl of 6 to 18 carbon atoms, and R2 and R3 are each independently straight or branched chain alkylene of 1 to 4 carbon atoms or a group of the formula CmH2m(OCkH2k)r where m is an integer from 1 to 4, k is an integer from 2 to 4, and r is an integer from 1 to
 20. 3. A compound according to claim 2 wherein R1 is alkyl of 6 to 18 carbon atoms, and R2 and R3 are both alkylene of 1 to 2 carbon atoms or a group of the formula CmH2m(OCkH2k)r where m is an integer from 1 to 2, k is 2, and r is an integer from 1 to
 20. 4. A compound according to claim 2 wherein R1 is a straight or branched chain alkyl of 6 to 18 carbon atoms.
 5. A compound according to claim 2 wherein R2 and R3 are both alkylene of 1 or 2 carbon atoms.
 6. A compound according to claim 5 wherein R1 is alkyl of 6 to 18 carbon atoms.
 7. A compound according to claim 2 wherein R2 and R3 are both a group of the formula CmH2m(OCkH2k)r where m is an integer from 1 to 2 k is 2, and r is an integer from 1 to
 20. 8. A compound according to claim 7 wherein R1 is alkyl of 6 to 18 carbon atoms.
 9. The compound according to claim 1 which is 2,3-bis(n-dodecylthio)-1,4-butanediol.
 10. The compound according to claim 1 which is 2,3-bis(n-octylthio)-1,4-butanediol.
 11. The compound according to claim 1 which is 2,3-bis(n-octadecylthio)-1,4-butanediol.
 12. The compound according to claIm 1 which is
 13. The compound according to claim 1 which is 